Where can I get a good silicon nitride

Where can I get a good silicon nitride? Now, this is a little bit of an introduction to this maybe a lot of people don't understand it. Right?

The aluminum nitride is a covalent bond, which belongs to the hexafil, the crystalline structure of the lead and zinc deposit, which is white or gray. AlN is atomic crystal, diamond-like nitrides, maximum stability to 2200 ℃. The temperature is high and the intensity decreases with the temperature. The thermal conductivity is good, the thermal expansion coefficient is small, it is a good heat resistant shock material. The ability to resist molten metal is strong, and is the ideal crucible material for molten iron, aluminum or aluminum alloy. Aluminium nitride is still an electrical insulator, and the dielectric properties are good, and there is also hope for electrical components. Gallium arsenide is a coating of nitrogen that protects it from ions when it is annealed. Aluminum nitride is also a catalyst for the conversion of boron to cubic nitride.